Guide to Use the Atlas

Table of Contents

About the Atlas

The Rodent Ultrastructure Atlas is a comprehensive collection of high-resolution microscopic images that show the intricate organization and detailed composition—the ultrastructure—of normal rodent tissues and cells. This resource will serve as a critical reference point for pathologists and researchers. By providing clear presentation of normal ultrastructure, the Atlas makes it easier to identify changes in tissues and cells that may result from exposures or disease. The site is available free of charge and designed to be simple to navigate. All images in the collection are annotated to include helpful descriptions and reference information.

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Organization

For ease of use, the Atlas is organized into chapters, each focused on a specific organ or organ system. Every chapter includes a set of annotated Toluidine Blue O-stained, semi-thin sections, and high-quality ultrastructural images with descriptions and references. All information has been reviewed by recognized experts and pathologists and vetted by the National Institute of Environmental Health Sciences Division of Translational Toxicology.

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Professional Judgment and Diagnostic Consistency

The pathologist has two primary responsibilities: to make correct morphologic diagnoses and to present those findings accurately in a narrative form. Adequate tissue preservation and preparation, familiarity with normal ultrastructure, recognition of ultrastructural artifacts and diagnostic consistency are essential for both.

The Rodent Ultrastructure Atlas supports these requirements. It provides extensive baseline imagery and information that will help pathologists and researchers recognize and understand changes at the ultrastructural level. It also presents the preferred terminology to use when making a diagnosis to facilitate uniformity in the reporting of findings.

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Structure of the Ultrastructural Diagnosis

Ultrastructural diagnosis should follow a consistent hierarchical structure. The tissue (site) should be listed first, followed in sequence by a subsite modifier, a morphologic (ultrastructural) diagnosis, and additional descriptive or distributional modifiers. For example, increased smooth endoplasmic reticulum of the hepatocyte cytoplasm should be recorded as:

Liver (site)

Hepatocyte (subsite)

Increased smooth endoplasmic reticulum (ultrastructural diagnosis).

Ultrastructural diagnosis of hyperplastic and neoplastic lesions should follow the same guidelines as non-neoplastic lesions.

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Multiple Subsites

When multiple subsites within the same tissue (site) exhibit the same ultrastructural lesion, each should be diagnosed using the guidelines outlined above.

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Citing the Atlas

The NTP Rodent Ultrastructure Atlas is publicly available for use worldwide. We request that you properly credit the authors for their work by citing the Atlas in the following format:

Dykstra, M. 2022. Muscle. In: Herbert, RA, Szabo, KA, Singletary E (Eds.), National Toxicology Program Rodent Ultrastructure Atlas.